How To Set Up DHCP Relay in pfSense for Windows Server 2022

Introduction

If you’ve ever tried wiring up DHCP across different subnets, you know it can get tricky. Sometimes, pfSense acts like a stubborn gatekeeper and refuses to forward DHCP requests properly, making devices hang or fail to get an IP. Setting up DHCP Relay bridges that gap, letting your Windows Server 2022 do its thing managing IPs for several network segments. This whole process might seem overkill, but trust me, once it’s configured correctly, devices just work without fuss.

This guide helps untangle that mess—disabling pfSense’s DHCP, turning on relay, and making sure it’s pointing the right way. Afterward, networking feels smoother, and troubleshooting becomes less of a headache. Perfect if you’re tired of static IP assignments or broken DHCP responses.

How to Fix DHCP Relay in pfSense for Windows Server 2022

Enable the DHCP Relay on pfSense — Why you need it

First off, setting up DHCP Relay is about forwarding DHCP requests from clients to your Windows Server. On some setups, pfSense’s default DHCP server conflicts or blocks requests, so turning it off and relaying them instead is the way to go. Usually, this applies if your DHCP server is on a different subnet or VLAN.

Expect that after this, devices on the network will get their IPs directly from Windows Server, not pfSense. On some routers, this process can be funky—sometimes the relay doesn’t work on the first try, and you gotta double-check rules.

Disabling pfSense’s DHCP Server — Prevents conflicts

• Head into Services > DHCP Server
• Select your interface, usually LAN
• Uncheck Enable DHCP Server for that interface
• Scroll down and click Save

This is super important—leaving DHCP enabled here while relaying requests can cause IP conflicts or confuse devices. On some installs, turning off DHCP here fixes a lot of weird issues, but sometimes you need a reboot or to clear the DHCP lease cache afterwards.

Turn on DHCP Relay — Why it matters

• Navigate to Services > DHCP Relay
• Check the Enable DHCP Relay box
• Select the interface where clients are—pick LAN or whatever is applicable
• Input the IP address of your Windows DHCP server (say, 192.168.1.100) in the relay server IP field
• Click Save and wait. Sometimes relays need a restart or a quick re-log in to pfSense for changes to stick.

This step is kinda sensitive. If you forget to specify the right interface or IP, DHCP requests just sit there like a bad joke. On some setups, relaying works right away, but on others, you gotta restart pfSense or reconfigure firewall rules.

Verify your settings and test — Because why not

• Plug in a device or spin up a VM that’s set to get DHCP automatically
• Ensure it’s connected to the same LAN segment where you’re relaying requests
• Check if it gets an IP from your Windows Server’s DHCP pool
• If not, look at logs under Status > System Logs, and check firewall rules for ports UDP 67 and 68—these are crucial for DHCP traffic

Sometimes, it’s just a matter of waiting for cache refresh or restarting pfSense. Weird quirks happen, especially if you’re switching from local DHCP to relayed ones. Just keep an eye on the logs—if DHCP requests are hitting pfSense but not forwarding, that’s the next thing to troubleshoot.

Extra tips & common hiccups — Because Murphy’s law

• Firewall rules matter — make sure UDP ports 67 and 68 are open for outgoing traffic. On pfSense, check under Firewall > Rules
• If devices still don’t get IPs, check the actual DHCP lease on Windows Server — maybe it’s full or misconfigured
• It can be weird, but sometimes switching the relay IP to the *gateway* that leads to your Windows Server helps
• If DHCP requests aren’t passing through, try rebooting pfSense or resetting the network interface — weird but sometimes necessary

Conclusion

Hooking up DHCP relay in pfSense isn’t rocket science, but it takes a bit of patience. Turning off pfSense DHCP, enabling relay, and pointing it at the right server IP fixes lots of IP assignment headaches. Keep an eye on the logs, double-check your firewall rules, and most things fall into place.

Once it’s working, DHCP issues become a lot less common, and managing multiple subnets gets way easier. If you’re still running into trouble, it’s worth looking into whether your Windows DHCP scopes are correct or if VLAN configurations block the traffic.

Summary

• Disable pfSense DHCP server on the relevant interface
• Enable DHCP relay and specify the Windows Server IP
• Make sure firewall rules allow DHCP UDP ports
• Test with a device to confirm IP assignment
• Check logs if things go sideways

Wrap-up

This setup has helped a lot of users get their DHCP working smoothly across different subnets. It’s a bit fiddly at first, but once it clicks, everything just flows. If this gets one step closer to fixing your network woes, then mission accomplished. Fingers crossed this helps!